Metal-working by electricity



\ ISL C. A. CADWELL.

METAL WORKING BY ELECTRICITY.

APPLICATION FILED JUNE 26. 1919.

Patented Feb. 8, 1921.

HTTOKNEYG.

UNITED STATES PATENT OFFICE.

CHARLES A. CADWELL, 0F CLEVELAND, OHIO, ASSIGNOR TO THE ELECTRIC RAILWAY IMPROVEMENT COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

METAL-WORKING BY ELECTRICITY.

Application filed June 26, 1919.

To all whom it may concern:

Be it known that I, CHARLES A. CADWELL, a citizen of the United States, and a resident of Cleveland, county of Cuyahoga, and State of Ohio, have invented a new and useful Improvement in MetalJVorking by Electricity, of which the following is a specification, the principle of the invention being herein explained and the best mode in which I have contemplated applying that principle, so as to distinguish it from other inventions.

Copper castings are usually made not from pure copper but from metal containing a small percentage of some other metal or metals, the function of the latter being to control the set and soundness of the metal. Copper alone is a diflicult metal to cast on account of the property which it possesses, which is peculiar to this metal alone, of dissolving and retaining in solid solution the oxid Cu,(), and also on account of the tendency to absorb various gases with which it may come in contact while in the molten state, the gases being occluded upon solidification with the result that the metal is porous. More than a trace of the oxid held in solid solution makes the resulting metal brittle and causes a low set, that is the mold fills with a depressed upper surface. Gas absorbed from the furnace or from the mold may account for porosity.

The successful casting of copper involves the melting of clean metal under cover from the air and from the gases of the furnace, or, what is more usually the case in all practical working, involves the reduction of ,the excess oxid which results from the melt .ing, and the expulsion of the absorbed gases,

by the addition of a flux or an alloying metal or by smelter manipulation. In smelt ers or refineries where the units are large, the condition of the molten copper is studied by means of small ladle castings and furnace conditions may be varied so as to bring about the desired results. In foundries the difiiculties are ordinarily overcome by adding a small percentage of another metal to form an alloy, the action of such metal being to expel the gases absorbed and to reduce the copper oxid back to metallic copper with the formation of an oxid which is floated oil as slag rather than held in solution.

The alloying metal or flux may be phos- Specification of Letters Patent.

Patented Feb. 8, 1921.

Serial No. 306,876.

treated with the alloying agents. Non-metallic agents are usually more difficult in using, and may require the preparation of casting ingot by a special melt during which a reaction is brought about which enters the required amount of the agent into the ingot copper to be used for castings. Boron carbid, a non-metallic reducing agent gives copper castings of a high degree of soundness, strength and electrical conductivity, but the successful use of this agent requires careful manipulation and a considerable degree of super-heat.

In view of the foregoing characteristics, the use of copper for pencil welding, either with gas or electric arc, has heretofore met with poor success. The metal, melted without cover, is porous from occluded gases and brittle from oxidation and from slag impurities. A successful pencil from an alloy copper would necessarily contain a high percentage of the alloying metal. The high temperature incident to pencil welding induces very rapid oxidation, and the volatile matter and slag resulting from the free use of the alloy agents make it diflicult to secure a clean sound cast or weld such as is required for instance for rail bonding.

I have found, however, that if to a pencil of ordinary commercial copper, is applied a thin coating of an alloy reducing agent such as silicon or manganese copper, the weld or cast resulting from are melting, such a penoil is better than if the reducing agent were alloyed uniformly throughout the body of the copper, the agent apparently being better situated. for the work of protecting the copper against the action of the air when applied as an envelop. Boron carbid as a pencil coating is especially applicable on account of the fact that the super-heat resulting from arc-melting is necessary to pro duce a reaction with this agent, while the fact that no slag results from its use adds to the superiority of this agent. Accordradars ingly, by properly coating the copper rod employed either directly as one electrode, or for insertion in an are generated between two terminals independent of such rod, a perfectly clean and solid body of molten copper is formed, suitable for welding the end of the conductor to the rail in the case of a bonding operation. By the same means a satisfactory terminal may be cast directly on the end of the conductor, ready to be subsequently welded or brazed to the rail. The adaptability of the process to various other uses will of course be obvious.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the steps and means hereinafter fully described and particularly pointed out in the claims, the annexed drawing and the following description setting forth in detail certain means and one mode of carrying out the invention, such disclosed means and mode illustrating, however, but one of various ways in which the principle of the invention may be used.

' In said annexed drawing Figure 1 is a transverse section through a rail showing the method of attaching a rail bond terminal thereto, using my improved method and apparatus; Fig. 2 is a cross-section showing the application of my method to the casting of a body of metal in a suitable mold which may take on any desired shape or form; and Fig. 3 is a. view partly in section and partly in elevation of the improved pencil which forms the feature of the invention.

Briefly stated, I have found that by coating a rod or pencil of metallic copper with boron carbid, such pencil may be employed directly in welding or casting operations of the kind described. Thus, as indicated in Fig. 1, such rod 1 may be made one terminal in a circuit 2, the other terminal of which consists of the rail 3. An arc will accordingly be formed between the end of such pencil 1 and the rail 3 adjacent the terminal 4c of the bond 5, which is suitably pressed against such rail. The end of the pencil, becoming molten, will drop into the cavity between the bond terminal and the rail, gradually building up abody which, as it solidifies, firmly unites the two parts in question together. lVhere the pencil is coated, as above explained, with the compound in question, the body of metal 6 remains free of oxid and compacts solidly in the space provided for it, so that a perfect union is provided.

In Fig. 2, I illustrate the manner in which a metallic pencil 7 of the same character is employed where the arc is formed between an independent carbon electrode 8 and the mold 9 likewise of carbon or similar refractory material, in which the molten metal is received. Such metal will here likewise build up a mass as free from oxid and bubbles as though cast under the most advantageous circumstances from a crucible. By disposing one end of a conductor 10 so as to project into the mold cavity, the mass of metal thus deposited in the latter will incorporate the terminal strands of the conductor and thus form a solid terminal or head on the latter.

In Fig. 3 is shown, partly in section, the appearance of the pencil 1 of copper with its coating 1" of boron carbid, the thickness of the coating being somewhat exaggerated. Preferably the carbid is mixed with a suitable Varnish, for example J apalac, thinned with the necessary quantity of turpentine to make it free flowing. The mixture is then applied either with a brush or by dipping the pencil into a bath of such mixture, whereupon a suflicient quantity will adhere for the purpose in hand.

The quantity of boron carbid required for reaction with the metal contained in the pencil is quite small, and for best results should be accurately gaged, since too little of the agent results in oxidized copper of low set and too much in a metal that is overreduced and is characterized by a rising in the mold and well known honeycombed structure. Accordingly, in order to secure a coating of uniform quantitative composition, I grind the boron carbid to a very fine powder and mix it with finely divided graphite in the proportions of approximately two parts of boron carbid to eight of graphite; then add boiled linseed oil and a few drops of benzin or other drier containing no mineral, thus obtaining a paint which will spread in a thin uniform coat. If necessary more than one coating of the resulting composition may be applied, or for certain diameters of wire such composition may require to be still further diluted.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the steps or mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention 2- 1. In metal working, the steps which consist in melting a metallic pencil and simultaneously adding a. reducing agent capable of forming an alloy with the metal of such pencil.

2. In metal working, the steps which consist in melting a metallic pencil and simultaneously adding an alloy reducing agent.

8. In metal working, the steps which consist in melting a metallic pencil and simultaneously adding boron carbid.

1. In metal working by electricity, the steps which consist in subjecting the metal to the electric arc, and at the same time adding a reducing agent capable of forming an alloy with such metal.

5. In metal Working by electricity, the

steps which consist in melting down a metallic pencil by means of an electric arc, and at the same time adding an alloy reducing agent. 6. In metal working by electricity, the steps which consist in establishing an electric arc between the end of a pencil of such metal and other suitable terminal, and at the same time adding boron carbid.

7. In a method of melting down copper for welding or casting operations, the steps 15 which consist in coating a pencil of such metal with an alloy reducing agent, and then subjecting such pencil to the electric arc.

8. In a method of melting down copper for welding or casting operations, the steps which consist in coating a pencil of such metal with boron carbid, and then establishing an electric arc between the end of such pencil and another suitable terminal. 25

Signed by me this 18 day of June, 1919.

CHARLES A. OADWELL. 

